【作者】 何静；

【导师】 黄守道； 雷雄；

【作者基本信息】 湖南大学 ， 控制工程（专业学位）， 2017， 硕士

【摘要】 在传统化石能源日益短缺的当下,可再生能源的地位越来越高。风能作为一种清洁、丰富的可再生能源受到了广泛的关注与应用,其中双馈风力发电系统凭借其优良的控制性能与经济特性受到了诸多使用者的青睐。电网中各式各样的用电装置,发电设备以及外界环境的诸多影响使得理想电网在实际应用中并不存在,实际应用的非理想电网中存在了大量的电能质量问题,其中以不平衡与谐波问题最为突出。工作在非理想电网环境下的双馈风力发电系统会受到电网中不平衡、谐波问题的影响,可能导致其转子中的电流波形畸变,转矩抖动,齿轮箱损害等问题,不但不能达到理想的发电效果,还会恶化电网中的电能质量并对双馈风力发电系统自身造成危害。对双馈风力发电系统中的背靠背换流器的控制策略进行设计,使在其控制下的双馈风力发电系统能较好的运行在非理想电网环境下,具有抵御谐波、不平衡等问题。由此,DFIG控制策略的设计在理论与实践上都具有相当重要的意义。文章对国内外风电的发展与现状进行了阐述说明,重点介绍了双馈风力发电系统及其现有的控制技术。为研究更为优越的控制技术,文章从双馈风力发电系统的数学模型着手,分别建立了非理想电网下双馈风力发电系统在静止的abc三相坐标下的数学模型以及在dq旋转坐标下的数学模型;在考虑不同频率的谐波以及不平衡现象的条件下对dq坐标下的模型进行了改进,针对背靠背结构的风机换流器构造了双PWM换流器的数学模型,并以此为基础,引入了三种谐振控制器:PR、PIR、VPI对风机换流器进行控制,在理论与仿真实验中对这些控制策略下的双馈风力发电系统进行了研究验证,得出了各种的优劣,其中VPI控制策略对于非理想电网下的双馈风力发电系统具有更加明显的优势。文章重点通过功率的角度对DFIG系统的控制器进行设计;在对换流器的底层控制,采用空间矢量调制的方法控制换流器的状态。文章最后通过功率传输关系的分析,结合数学模型提出了适用于双馈风力发电系统的直接功率控制策略,并将其与VPI控制策略相结合,构造出VPI-DPC的控制方式,通过理论分析以及仿真验证得出了该种控制策略的有效性与优越性。更多还原

【Abstract】 In the current shortage of traditional fossil energy,renewable energy is becoming more and more important.As a kind of clean and renewable energy,wind energy has attracted wide attention and application.Doubly fed wind power generation system has been favored by many users because of its excellent control performance and economic characteristics.There are many kinds of power equipment,power generation equipment and environment in the grid,which make the ideal grid do not exist in practical application.There are a lot of power quality problems in the non ideal power grid,especially the imbalance and harmonic problems.Doubly fed wind power generation system,which is working in a non ideal grid environment,is affected by unbalanced and harmonic problems in the power grid.It may cause the distortion of the current waveform in the rotor,the torque jitter and the gear box damage.Not only can not achieve the ideal power generation effect,but also will deteriorate the power quality in the power grid and cause harm to the doubly fed wind power generation system itself.The control strategy of back-to-back converter in doubly fed wind power generation system is designed.Doubly fed wind power generation system can operate better in non ideal grid environment.And has the ability to withstand harmonics,imbalances and other issues.Therefore,the design of DFIG control stra tegy is of great significance both in theory and practice.This paper expounds the development and present situation of wind power at home and abroad.The doubly fed wind power generation system and its existing control technology are mainly introduced.In order to study the better control technology,this paper starts with the mathematical model of doubly fed wind power generation system.The mathematical model of doubly fed wind power generation system under stationary ABC three-phase coordinates is established.And the mathematical model under DQ rotating coordinate is established respectively.Considering the harmonic and unbalanced phenomena of different frequencies,the model under the dq coordinate is improved.A mathematical model of double PWM converter is constructed for the fan converter of back to back structure.Three resonant controllers are introduced.The PR,PIR,and VPI control strategies control the fan converter.In theory and simulation experiments,the doubly fed wind power generation system under these control strategies is studied and validated.The advantages and disadvantages of various control strategies are obtained.Among them,the VPI control strategy has more obvious advantages for doubly fed wind power generation system under imperfect power grid.The article focuses on the power point of view of the DFIG system controller design.In the bottom of the converter,the space vector modulation method is used to control the converter state.The power transfer relationship is analyzed after the article is rented.Combined with the mathematical model,a direct power control strategy for doubly fed wind power generation system is proposed.The control strategy of VPI-DPC is constructed by combining it with VPI control strategy.Through th eoretical analysis and simulation,the effectiveness and superiority of the control strategy are obtained.更多还原